The Riverhead woman accused in September of shooting her estranged boyfriend was angry he wouldn’t marry her and she threatened to kill him and herself moments before firing the gun, a prosecutor alleged at her arraignment in Suffolk County Court Thursday.

Patchita Tennant, 42, pleaded not guilty before Suffolk County Supreme Court Judge John Collins on upgraded charges that include a top count of attempted murder for the Sept. 5 incident involving Andrew “Silas” Mitchell inside the home they once shared on Pleasure Drive in Flanders.

“[Mr. Mitchell] was in the master bathroom of their home shaving when Ms. Tennant kicked open the bathroom door and indicated to him, ‘You aren’t going to marry me, I’m going to kill you and then kill myself,’ ” Assistant District Attorney Eric Aboulafia said during the arraignment. “She proceeded to make good on that threat and shot Mr. Mitchell [three times].”

Mr. Aboulafia said Mr. Mitchell remained at Stony Brook University Hospital for eight days following the incident and had a three-hour surgery to save his life. He said Mr. Mitchell later had part of his lung removed due to injuries from the shooting, which included taking two shots to the chest and one to an arm.

Ms. Tennant, who was surrounded in court by more than a dozen supporters, remains free on the $500,000 bond she initially posted in town court, though Judge Collins cautioned that she must resolve passport issues. A non-citizen, Ms. Tennant had been living in the U.S. under an expired passport, the judge said. She has since applied for a renewal and Judge Collins said that must be immediately turned over to the court.

In addition to the attempted murder charge, she is facing felony charges of first-degree assault, criminal use of a firearm and assault with intent to cause physical injury with a weapon.

The shooting incident occurred that Thursday evening shortly before 8:20 p.m., when police were called to the home and advised to be on the lookout for Ms. Tennant, who was reported to have fled the scene with the couple’s 3-year-old daughter.

The search for Ms. Tennant and the child, which led police to issue a statewide Amber Alert, spanned about 18 hours. The child was located with a family member late the next morning and Ms. Tennant, whose vehicle was found in Middle Island, turned herself in to Southampton police around 3 p.m. that Friday.

At her initial arraignment in Southampton Town Justice Court, Sept. 7, Ms. Tennant’s attorney, Austin Manghan, argued his client was acting in self defense. Mr. Manghan said the gun belonged to Mr. Mitchell and that she wrestled it away before shooting him. He added that the child was not present at the time of the shooting and that Ms. Tennant did not have the gun with her when she fled. He said the gun belonged to Mr. Mitchell.

Mr. Aboulafia previously said Ms. Tennant and the couple’s daughter had been at a relative’s house when she realized she might not have enough clothes for her daughter and went alone to the house she owned with Mr. Mitchell to get more.

Mr. Manghan also previously said Ms. Tennant had never seen the .38-caliber gun before and was unaware that Mr. Mitchell owned it. He said Mr. Mitchell, who he accused of beating his client during the decade they were together, tried to shoot Ms. Tennant after he was shot, but the gun had no more bullets.

Mr. Manghan did not raise those allegations again Tuesday.

Ms. Tennant is due back in court for a conference on Thursday, Dec. 12.